From: H.G. Muller <h.g.muller@hccnet.nl>
Date: Wed, 8 Jun 2011 15:11:31 +0000 (+0200)
Subject: Fix round-robin schedule
X-Git-Url: http://winboard.nl/cgi-bin?a=commitdiff_plain;h=0fd972d551d13b21ee43524c2e6d36691710b7ba;p=xboard.git

Fix round-robin schedule

The first round was played twice, and the formulas used to derive the
pairing were not even-odd resistant anyway. Both even and odd number of
participants should work now.
---

diff --git a/backend.c b/backend.c
index 6645db1..d04fd3d 100644
--- a/backend.c
+++ b/backend.c
@@ -9746,9 +9746,9 @@ Pairing(int nr, int nPlayers, int *whitePlayer, int *blackPlayer, int *syncInter
 	    *whitePlayer = curRound;
 	    *blackPlayer = nPlayers - 1; // this is the 'bye' when nPlayer is odd
 	} else {
-	    *whitePlayer = curRound - pairingsPerRound + curPairing;
+	    *whitePlayer = curRound - (nPlayers-1)/2 + curPairing;
 	    if(*whitePlayer < 0) *whitePlayer += nPlayers-1+(nPlayers&1);
-	    *blackPlayer = curRound + pairingsPerRound - curPairing;
+	    *blackPlayer = curRound + (nPlayers-1)/2 - curPairing;
 	    if(*blackPlayer >= nPlayers-1+(nPlayers&1)) *blackPlayer -= nPlayers-1+(nPlayers&1);
 	}
     } else if(appData.tourneyType > 0) {